Palliative surgery in neonates with a single right ventricle (RV), the Norwood 1 procedure, carries the highest risk for mortality and morbidity of all cardiac surgical procedures performed in infancy. The Single Ventricle Reconstruction (SVR) Trial is an ongoing Pediatric Heart Network (PHN) study designed to compare one year outcomes between two surgical modifications of the Norwood 1 procedure. The two modifications differ in their potential effect on RV myocardium: the modified Blalock-Taussig shunt (MBTS) results in a diastolic run-off of blood from the aorta to the pulmonary arteries that may compromise coronary blood flow, while the RV-to-pulmonary artery (RV-to-PA) shunt avoids this potential coronary artery steal phenomenon, but has a long term risk of right ventricular damage from a right ventriculotomy. The primary hypothesis of the SVR Trial is that the RV-to-PA shunt will have a lower incidence of death or transplant at one year of age. There is an ongoing risk of death or transplant extending beyond one year in this patient population, especially as planned open heart surgery is performed between 18 months and 3 years of age. This multicenter prospective follow-up study is designed to extend comparison of clinical outcome and RV performance between survivors of the RV-to-PA shunt and MBTS up to age 4 years. The primary aim is to compare the intermediate-term combined endpoint of death or transplant between the two groups with the hypothesis that the RV-to-PA shunt will have a lower incidence of death or transplantation compared the MBTS at 4 years of age. Secondary aims will include comparison of neurodelopmental outcome, health-related quality of life, RV function, somatic growth, pulmonary artery growth, the incidence heart failure, arrhythmias and the operative and post-operative course following Fontan completion. All subjects enrolled in the SVR Trial who survive to completion at 14 months of age will be eligible for inclusion. Data will be collected at the time of enrollment, at the time of the Fontan surgery (expected to occur between 18 months-3 years of age) and at age 4 years. An application to support a Clinical Research Skills Development Core is also included in this proposal. Relevance to public health: Surgery for hypoplastic left heart syndrome has the highest incidence of death or transplantation of all congenital heart disease lesions. The results of this multicenter, prospective study will provide important information regarding the optimal neonatal surgical intervention for this lesion. (End of Abstract)